Desulfurization of a hydrocarbon oil



.HAU D GO wom DMN. HWDRHDWND J. MCAFEE DESULFURIZATION oF A HYnRocARBoN om Fiied oct. 28, 1948 Dec. 23, 1952 mmv @Nv @NV @Nv Y MAUWUME "JH mmmnnm AWE@ NMO :DDUMFP Patented Dec. 23, 1952 DESU-LFURIZATION OF A HYDROCARBON OIL JerryMcAfee, Port Arthur, Tex., assigner `to Gulf Oilv Corporation,lPittsburgh, Pa., a corporation` of Pennsylvania ApplicationQOctobervZS, 1948,"S`eria1`No. 57,011

(Cl. 196.-2S)

Il Claims. 1

This invention relates to an'improved process for vdesulfurizing a hydrocarbon oil and in particular'relates to improvements in'hydrodesulfurization of a hydrocarbon oil'by treating vapors thereof inthe presence Yof a metal orimetal'oxide to formfa sulfide followed by Aperiodic regeneration'of the metal or metal oxide:

It has been knownlprevio'usly vthat-it is'possible to lremove sulfur"compounds from a hydrocarbon'oil by contacting lvapors thereof "with hydrogen and va contact having the sulfur-absorbing properties of metals 'of the iron'A group. The sulfur absorbing `contact is converted into an iron group metal suliide and Ycarbonaceousl material is simultaneouslydeposited thereon" in f relatively large amounts. The contact is periodical-lyregenerated by-burning oif the'carbonaceous material and converting the iron Vgroup lmetal sulfide into the iron group metal'oxide by oxidation. In `certainscasesA the metal oxide then is reduced but Yin any case the oxide Aor the reduced metal is KJagaiircontacted wit-hthe sulfurcon -taininghydrocarbon vapors.

Considerable difficulty has been encountered during the regeneration of the `desulfurization contact. The carbonaceous -material is deposited on the vcontact in unusually large amounts and is of a tarryor asphaltic nature which tends to plug the catalyst-bed. Under certain conditions, particularly with heavy stocks, this plugging is so Iserious that regeneration by combustion fis precluded simply because the contact lbed `is plugged so badly that it' is impossible tolforce suiiicient regenerating medium through it. Furthermore, as indicated above,l it is necessary not only vtopremove the carbonaceous material but also tolconvert the ircngroupmetal suliideback into the oxide. This vreouiires additional amounts of regenerating medium and Vfurther complicates the problem.' It :has also been found that' the hydrodesulfurization contacts tend to become :agglomerated and it is believed lthat lthis fagglomeration is associated with the formationzoi a alowfmelting jironA group metalA sub-.suliide which tends to fuse `and stick Vthe catalyst pelletsv to,v

gether. This regeneration, therefore, involves acute problems not encountered with the; regeneration of conventional cracking and .like contacts.

Anobject of my invention is to `provide an improved -hydrodesulfurization process in'which the foregoing diiculties are reduced'or eliminated. Another object is to provide a hydrodesulfurization process in which the regeneration of the contactis simplified. Another object is to.

provide -anv `improved hydrodesulfurizationf lprocess utilizing an -iron Agroup metal orqmetaloxide' as the 'absorbent for the sulfur whereinI the regeneration of the iron ygroup metal-,can .be `aocomplished inA a relatively shortperiodof time and with a smaller amount of. regenerating rnedium. Y Another object is to reducelthefamount of hydrocarbons lostY during .hydrodesulfurization Other objects'. will .appear hereinafter.

These Aand other. .obj ects are: :accomplished: by my invention which .includes terrninatingtthe hydrodesulfurization or ithe hydrocarbon'when; a substantial amount of carbonaceous. material and sulde has been formed .'on the isulfureabsorbing contact, .treating this 'zcontact .wtihliydrogen at an elevated temperaturexand .pressure to convert a substantialamountof thecarbonaceous material into hydrocarbon vaporsrvthen subjecting the contact to a regenerationtreatment to remove most of the remaining 4ca'rbonaceous material and to reconvert thesulfuriiabsorbing material into `its original form and ,again treating vapors of the hydrocarbon oil with hy'- drogen in the presence of .the regenerated'lcontact.

In the following examplesxand rdescriptionI have set Vforth severalof thepreferredembodiments lof myinvention but itis -tobe understood that these are given byiway of illustration fand not in limitation thereof.

In-.the accompanying drawing .Ivhave illustrated apparatus in which my improved process .may

39 .and is a mixture Yof recycle hydrogen flowing through valve 38 plus make-uphydrogen introduced through conduit 40. This mixture ofchy-f drogen and hydrocarbon .vapors .flows :through heater 6, line i, valve 8, andconduit 0v into .reactorl, which-.contains a bed of sulfur-absorbe ingmetal or metal -oxicle Ycna rporous'rcarrier.

The mixture of thev hydrogen 'and'hydrocarboni' vapor passes into intimate contact with 1 the sulfur-absorbing material in reactor I0 :an'd thek sulfur contained in the hydrocarbon oil .isi re moved by absorption to form lironigroup metalv The eiluent from reactor I'0,fi..e. the hydrogen and the desulfurized hydrocarbon vapors then pass through conduit Il, valve I 2,A conduit AI3 and heat exchanger 4, which serves to preheat the charge stock, and then through cooler 48, in which liquid hydrocarbons are condensed. The ellluent then flows through line I4 into high pressure separator I5 Where the liquid hydrocarbons are separated from the hydrogen gas. This liquid product passes through line I6, heat exchanger I1, line I8 and valve I9 into low pressure separator 20. The liquid desulfurized product from low pressure separator 24 is Withdrawn through valve 2I and conduit 22. In low pressure separator a small amount of hydrogen absorbed in the liquid product is evolved and is pumped by pump 25 through valve 23, lines 24 and 26, into separator 21. In separator 21 small amounts of entrained hydrocarbon liquids are separated and are Withdrawn by Way of line 28, valve 29, and line 30, which joins the desulfurized product line 22. The gases from separator 21 are Withdrawn through line 3| and are combined with the high pressure hydrogen separated in high pressure separator I5, which hydrogen is withdrawn by Way of line 32 and recycle hydrogen compressor 41. This combined hydrogen then ows through line 34 and valve 35 into recycle hydrogen reservoir 36. This recycle hydrogen is withdrawn as needed through line 31 and passes through valve 38 and line 39, into heater G. Make-up hydrogen is added continuously or intermittently through line 40. Small amounts of recycle hydrogen are periodically bled from reservoir 36 to enable this addition of fresh or make-up hydrogen through line 40, thus maintaining the purity of the recycle hydrogen stream at any desired level.

After the hydrocarbon vapors and hydrogen have passed through the contact bed in reactor I0 for a sufcient period of time, the contact pellets will become coated with carbonaceous material and the iron group metal or metal oxide thereon will become converted to a substantial extent into the iron group metal sulfide. It is desirable to regenerate the contact when this deposit of carbonaceous material undesirably affects the passage of the reactants through the chamber or when suicient iron group metal sulde has been formed to reduce the sulfur-absorbing capacity of the contact. This reduction in sulfur-absorbing capacity usually takes place when about to 60 per cent metal sulde has been formed. It can be determined When substantial amounts of HzS appear in the effluent. At this stage it is desirable to interrupt the process and to regenerate the contact in reactor I0.

During the on-stream period Valves 4I, 42 and 43 in lines 44, 45 and 46, respectively, remain closed. At the completion of the on-strearn period valve 2 is closed and hydrogen is permitted to flow through furnace 6 and lines 1 and 9 into contact I. This heated hydrogen tends to convert the carbonaceous deposit to a substantial extent into hydrocarbon vapors. These vapors pass with the unreacted hydrogen through conduit II, valve I 2, line I3, conduit I4, heat exchanger 4, and cooler 48, into the high pressure separator where the hydrogen is separated from the condensed hydrocarbons and is passed to recycle hydrogen reservoir 36. The liquid hydrocarbons are separated in separator 20 and are recovered as a useful product. The recycle hydrogen is thus used to remove a large part of the carbonaceous material from the contact, recovering it as useful hydrocarbon without any additional equipment.

After a substantial amount of carbonaceous material has been removed, the contact bed in reactor I0 is subjected to a treatment which will reconvert the contact into substantially its original form. This is accomplished by first opening valve 49, which allows the hydrogen stream to by-pass the reactor through line 50, and then closing valves 8 and I2. The pressure in reactor I0 is released by opening valve 43 and purge gas such as steam is pased through the reactor by introduction through conduit 45 and valve 42 and removal through valve 43 and conduit 46. Alternatively a vacuum may be used instead of a purge gas to remove the residual hydrogen from the reactor.

Regeneration gas, such as a mixture of air or oxygen and steam, is then introduced into the reactor, after` closing valve 42, through conduit 44 and valve 4I. This oxygen containing mixture removes the carbonaceous material on the contact by combustion and the products of combustion pass out of the reactor by Way of conduit II, valve 43 and conduit 46. The oxygen also converts the iron group metal sulde into iron group metal oxide with formation of sulfur dioxide. After removal of most of the remaining carbonaceous material has taken place and the iron group metal sulde has been substantially reconverted into the oxide, the flow of oxygen containing gas mixture is terminated by closing valve 4I. A purge gas such as steam is then introduced through conduit 45 by Way of valve 42 in order to remove any remaining combustion gases, and valves 42 and 43 are then closed. In the event that a reduced metal contact is to be used valves S and I2 are opened and valve 49 is closed and recycle hydrogen gas is introduced into reactor I0 until most of the metal oxide has been converted into the metal by reduction. The onstream reaction then is carried out as previously described by opening valve 2 and introducing the hydrocarbon charge. If a reduced Contact is not to be used the hydrogen and hydrocarbon are both charged to the contact as initially described Without the reduction to convert the oxide to the metal.

It will be obvious to one skilled in the petroleum art that many modifications can be made in the foregoing Without departing from the spirit or scope of my invention. Thus it is usually desirable to have more than one reactor so that one contact mass may be on-stream While the contact mass in another reactor or reactors is undergoing treatment to remove carbonaceous material and/or to remove residual carbonaceous material and suldes by combustion. The effluent from this second reactor then would be returned to the on-stream reactor as recycle hydrogen. While recycle hydrogen for the preliminary removal of the carbonaceous material is advantageous, hydrogen from any source, such as the fresh or make-up hydrogen, may be used. Also the recovery of the hydrocarbons formed during the destructive hydrogenation is advantageously carried out in the apparatus used to recover the desulfurized hydrocarbon during the on-stream reaction. However any other method of recovery may be used. My invention is applicable to desulfurization processes utilizing a uidized fixed bed or a fluidized circulating contact as well as drogenation 'aresatisfactory ffiiyaoafboii-tqgas-and icessiveqartw farmation. `Asdisclosed;in copending applications kSerial Nos. 699,671A and 699,672,1led ASeptembt-Zr 27,

1946,`in'the'n`ames of Horne'and Junge, now U; S. Patents 2,516,876 and 2,516,877 respectivelyksuperior' results are obtained if the contact contains a substantial amount of Vthe oxide of the metal. Inits preferred form my inventioninvolvesthe use of a contact containing a large amount ofan iron group metal oxide, especially nickel oxide. However, the invention is equally applicable to the use of a Contact containing ,the iron group metal entirely or `substantia'lly'enti'rely in the metal form. While the less preferably about 2 to 30 per cent. Examples of suitable porous carriers are silica gel, activated alumina, Magnesol, Porocel, Alfrax, kieselguhr and silica-alumina cracking catalysts of conventional types, prepared synthetically or by acid treatment of natural clays.

The temperature for the desulfurization treatment preferably should be between about 600 and 950 F. A temperature of 600o to about 800 F. is preferred for low boiling hydrocarbons such as gasoline and a temperature of aboutr750 to 950 is best for heavy hydrocarbons, such as reduced and topped c rudes` and crude petroleum. Theinventicn is of particular value in connection with'such heavy hydrocarbons since they tend to-deposit abnormal amounts of tars and carbon during the desulfurization treatment. `Hydrogen inamounts of at least 100 and preferably above 4000 cubic feet per barrel of oil should be used. Pressures between about 100 and 1000 p. s. i. g. are preferred. The space velocity preierably should'vary from 0.2 to 6.0 volumes of 'liquid hydrocarbon per volume of catalyst.

The hydrogen treatment to remove the carbonaceous material should be carried out at a temperature and pressure sufilcient to convert the carbona'ceous material into hydrocarbon vapor. Thus conditions usually used for destructive hy- In general, the higher the temperature and pressure and the longer the time the greater will be the reduction of the -carbonaceous deposit. The iron group metal, oxide and/or sulfide acts as a hydrogenation catalyst during this part of the process and` assists in the destrictive hydrogenation of the tar, asphalt, etc. into useful hydrocarbon vapors. The temperature is preferably at least as high as the temperature used during the desulfurization step. However any temperature between 600 and lll-00 F. can be used. The temperature should not be high enough to cause sintering of the contact. A pressure of between about 100 and 2000 p. s. i. g. is desirable. The total amount of hydrogen varies from 5 to 5000 standard cubic Ieet per cubic feet of contact.

Example: Whole desalted West Texas crude having a gravity of 34.6 A. P. I. and a sulfur content of 1.51 per cent was vaporized and the vapors together with hydrogen were passed through a reactor filed with pellets of a contact containing 21.9 per cent nickel oxide deposited on a silica-alumina cracking catalyst (Harshaw yper volume of contact; total gas rate 5547 s. c. e./bb1. of charge; hydrogen gas purity 84.9 per cent H2; process period length 4 hours. After each process period of 4hours the oil'flow was stopped and the hydrogenv gas circulation continued for 30 minutes at the same rate, temperature, andpressure as during the processing period. The reactor was then depressured and purged with steam The contact was then regenerated by passing steam-through vthe reactor at a rate of 10S-8 pounds per hour preheatedto a reactor inlet temperature of 850 F. yAir 'was added to the steam at an average rate of 2773 s. c. f. h. so controlled that the maximumv catalyst temperature approached but did not'exceed approximately l200 F. An average' regeneration time of 3.33 hours was required to complete the regeneration during the 6 cycles comprising this test run. The hydrogen gas and oil vapors then were again passed through the reactor, thus starting another cycle. Six cycles were completed in this manner. The total liquid product obtained in the 6 cycles had a gravity'of 39.8 A. P. I. and a sulfur content of 0.50 per cent. These inspections were in good agreement with those of previous test runs at the same conditions. To'aford a basis of comparison, test 'runs were made under the same conditions except that the hydrogen treatment prior to regeneration was notl used. `It was found that the hydrogen treatment in accordance with the invention reduced the regeneration steam requirement 872 pounds per barrel charge to 459 poundsper barrel charge. The yield of liquid product (C5 and heavier) was increased by the hydrogen treatment prior to regeneration from 90.2 weight per cent to 92.2 weight per cent while the production of purge oil (oil recovered from thereactor upon depressuring the reactor vand steam purging) was decreased from` 1.05 weight per cent to 0.04 per cent by'weight.

An outstanding advantage of the invention is that it reduces the amount of carbonaceous -material which must be removed during the regeneration by combustion. This reduces the vregeneration requirements suchA as the time, reactants and size of equipment necessary for regeneration. In addition, relatively large amounts of useful hydrocarbons are recovered which would otherwise be lost. This is due not only to the conversion of the carbonaceous material butalso to the recovery of the hydrocarbons deposited thereon which are normally at least partially lost in the purge gases.

I claim:

1. The process for removing sulfur compounds from a hydrocarbon oil which comprises treating a hydrocarbon oil which contains sulfur compounds while substantially in vapor form with hydrogen in the presence of a contact comprising a porous carrier on which is deposited a metalliferous material selected from the group consisting of iron group metals and their oxides at a temperature between about 600 and 950 F. and a pressure between about 100 and 1000 p. s. i. g. terminating said treatment when a substantial amount of carbonaceous material and sulde has been formed on the contact, treating the contact with hydrogen at a pressure between about 100 and 2000 p. s. i. g., at a temperature between about 950 and 1400 F. whereby a substantial amount of the carbonaceous material on the contact is converted into hydrocarbon vapors without substantial conversion of the sull-ide material on the contact into hydrogen sulfide, subjecting the contact to a combustion regeneration treatment to remove most of the remaining carbonaceous material and to convertl said metalliferous material into its original form and again treating a hydrocarbon oil which contains sulfur compounds while substantially in vapor phase with hydrogen in the presence of the regenerated contact under the conditions specified above.

2. The process for removing sulfur compounds from a hydrocarbon oil which comprises treating a hydrocarbon oil which contains sulfur compounds while substantially in vapor form with hydrogen in the presence of a contact comprising a porous carrier on which is deposited a metalliferous material selected from the group consisting of iron group metals and their oxides at =a temperature between about 600 and 950 F. and a pressure between about 100 and 1000 p. s. i. g. terminating said treatment when a substantial amount of carbonaceous material and suliide has been formed on the contact, treating the contact with hydrogen at a pressure between about 100 and 2000 p. s. i. g., at a temperature between about 950 and 1400" F. whereby a substantial amount of the carbonaceous material on the contact is converted into hydrocarbon vapors without substantial conversion of the sulfide material on the contact into hydrogen sulde, -adding these converted hydrocarbon vapors to the desuliurized hydrocarbon product, subjecting the contact to a combustion regeneration treatment to remove most of the remaining carbonaceous material and to convert said metalliferous material into its original form and again treating a hydrocarbon oil which contains sulfur compounds while substantially in vapor phase with hydrogen in the presence of the regenerated contact under the conditions specified above.

3. The process for removing sulfur compounds from a hydrocarbon oil which contains sulfur compounds and which is selected from the group consisting of crude, reduced crude and topped crude, which comprises treating said hydrocarbon oil substantially in vapor form with hydrogen in the presence of a contact comprising a porous carrier on which is deposited a metalliferous material selected from the group consisting of iron group metals and their oxides at a temperature between about 750 and 950 F. and a pressure between Iabout 100 and 1000 p. s. i. g. terminating said treatment when a substantial amount of carbonaceous material and sulde has been formed on the contact, treating the contact with hydrogen at a pressure between about 100 and 2000 p. s. i. g., at a temperature between about 950 and 1400 F. whereby a substantial amount of the carbonaceous material on the contact is converted into hydrocarbon vapors without substantial conversion of the sulde material on the contact into hydrogen sulfide, subjecting the contact to a combustion regeneration treatment to remove most of the remaining carbonaceous material and to convert said metalliferous material into its original form and again treating said hydrocarbon oil substantially in vapor phase with hydrogen in the presence of the regenerated contact under the conditions specied above.

4. The process for removing sulfur compounds from a hydrocarbon oil which contains sulfur compounds and which is selected from the group consisting of crude, reduced crude and topped crude, which comprises treating said hydrocarbon oil substantially in vapor form with hydrogen in the presence of a contact comprising a porous carrier on which is deposited a metalliferous material selected from the group consisting of iron group metals and their oxides at e temperature between about 750 and 950 F. and a pressure between about and 1000 p. s. i. g. terminating said treatment when a substantial amount of carbonaceous material and suliide has been formed on the contact, treating the contact with recycle hydrogen at a pressure between about 100 and 2000 p. s. i. g., at a temperature between about 950 and 1400 F., whereby a substantial amount of the carbonaceous material on the contact is converted into hydrocarbon vapors without substantial conversion of the sulfide material on the contact into hydrogen sulfide, adding these converted hydrocarbon vapors to the desulfurized hydrocarbon product, subjecting the contact to a combustion regeneration treatment to remove most of the remaining carbonaceous material and to convert said metalliferous material into its original form and again treating said hydrocarbon oil substantially in vapor phase with hydrogen in the presence of the regenerated contact under the conditions specified above.

JERRY MCAFEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. THE PROCESS FOR REMOVING SULFUR COMPOUNDS FROM A HYDROCARBON OIL WHICH COMPRISES TREATING A HYDROCARBON OIL WHICH CONTAINS SULFUR COMPOUNDS WHILE SUBSTANTIALLY IN VAPOR FORM WITH HYDROGEN IN THE PRESENCE OF A CONTACT COMPRISING A POROUS CARRIER ON WHICH IS DEPOSITED A METALLIFEROUS MATERIAL SELECTED FROM THE GROUP CONSISTING OF IRON GROUP METALS AND THEIR OXIDES AT A TEMPERATURE BETWEEN ABOUT 600* AND 950* F. AND A PRESSURE BETWEEN ABOUT 100 AND 1000 P.S.I.G. TERMINATING SAID TREATMENT WHEN A SUBSTANTIAL AMOUNT OF CARBONACEOUS MATERIAL AND SULFIDE HAS BEEN FORMED ON THE CONTACT, TREATING THE CONTACT WITH HYDROGEN AT A PRESSURE BETWEEN ABOUT 100 AND 2000 P.S.I.G., AT A TEMPERATURE BETWEEN ABOUT 950* AND 1400* F. WHEREBY A SUBSTANTIAL AMOUNT OF THE CARBONACEOUS MATERIAL ON THE CONTACT IS CONVERTED INTO HYDROCARBON VAPORS WITHOUT SUBSTANTIAL CONVERSION OF THE SULFIDE MATERIAL ON THE CONTACT INTO HYDROGEN SULFIDE, SUBJECTING THE CONTACT TO A COMBUSTION REGENERATION TREATMENT TO REMOVE MOST OF THE REMAINING CARBONACEOUS MATERIAL AND TO CONVERT SAID METALLIFEROUS MATERIAL INTO ITS ORIGINAL FORM AND AGAIN TREATING A HYDROCARBON OIL WHICH CONTAINS SULFUR COMPOUNDS WHILE SUBSTANTIALLY IN VAPOR PHASE WITH HYDROGEN IN THE PRESENCE OF THE REGENERATED CONTACT UNDER THE CONDITIONS SPECIFIED ABOVE. 